Can I tell the gender of my Bantams by their feathers?

My mom grew up on a farm, and has seen many, many chicks hatch. She says that the chicks with the little scruffy feathers on the top will be roosters. Is she right, or does that happen to all chickens, even if they are male/female? I am new to raising chickens, so this will also help in the future! I can supply picture if needed.